[Plugin: Google XML Sitemaps] It builds error format URLs in the XML file automatic!!!

Help,
when it builds sitemap.xml, gives wrong format URLs in the file,
such as:
http://gkoo.net//about/
You can see that a additional “/” was included in the URL
and the google webmaster tool will notify to me that the xml file contains dynamic URLs.

How to…?

And I think it mayby because of the .htaccess, but i am not sure.
it’s my .htaccess file

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

# BEGIN WPSuperCache
<IfModule mod_rewrite.c>
RewriteCond %{QUERY_STRING} !.*s=.*
RewriteCond %{QUERY_STRING} !.*attachment_id=.*
RewriteCond %{HTTP_COOKIE} !^.*(comment_author_|wordpress|wp-postpass_).*$
RewriteCond %{DOCUMENT_ROOT}/wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html -f
RewriteRule ^(.*) /wp-content/cache/supercache/%{HTTP_HOST}/$1/index.html [L]
</IfModule>

# END WPSuperCache

Oh!
One info more, it does not appear when i build the sitemap manual.

Thanx!